NatHERS Tool tip

Monica Vandenberg reports on a new feature in FirstRate5 for the information of Accredited Thermal Performance Assessors who use FR5

Effective Eaves in FR5

A new feature has been introduced in FR5 v5.2.7 to enable a graphic representation of the position of eaves being calculated.

In FR5, when you create eaves for a wall, a blue line then appears on the drawing canvass; this eave line is moveable and users can select it, move it around and change the length by grabbing the end nodes.

This ability to move this line gives the impression that users can draw angled eaves, however this is not the case as the CSIRO Chenath thermal calculation engine can only deal with eaves parallel to the wall.

A tick box is in the ‘calculated’ tab and is activated automatically when the eave is created.

In FR5, if a user draws an angled eave, FR5 automatically corrects this eave to make a parallel eave based on the furthest point of the eave away from the wall. The graphical representation of the parallel eave is only visible when the wall it is attached to is selected on the drawing canvass. Previously this correction was not visible to the user, but in v5.2.7 the tick box enables users to see the effective eave FR5 that has been calculated.

Check out page 130 of the FR5 manual where you will find a tip box about this function.

Eaves Tip: If a non-parallel eave extends for a reasonable length, it is then advisable to break the wall with the corresponding eave into segments. This is so that the shading does not become excessive in areas where the eave is not projecting.